Subband Encoding of High Dynamic Range Imagery

ABSTRACT

The transition from traditional 24-bit RGB to high dynamic range
(HDR) images is hindered by excessively large file formats with no
backwards compatibility. In this paper, we propose a simple approach
to HDR encoding that parallels the evolution of color television
from its grayscale beginnings. A tone-mapped version of each HDR
original is accompanied by restorative information carried in a
subband of a standard 24-bit RGB format. This subband contains a
compressed ratio image, which when multiplied by the tone-mapped
foreground, recovers the HDR original. The tone-mapped image data
may be compressed, permitting the composite to be delivered in a
standard JPEG wrapper. To naive software, the image looks like any
other, and displays as a tone-mapped version of the original. To
HDR-enabled software, the foreground image is merely a tone-mapping
suggestion, as the original pixel data are available by decoding
the information in the subband. We present specifics of the method
and the results of encoding a series of synthetic and natural HDR
images, using various published global and local tone-mapping
operators to generate the foreground images. Errors are visible
in only a very small percentage of the pixels after decoding, and
the technique requires only a modest amount of additional space for
the subband data, independent of image size.

Some of the links on these pages are for HDR images you may
wish to compare in Radiance RGBE
format.Depending on your system,
you may download a viewer for this format from one of the following websites: